Build: Fix invalid version string in assembly info for dotnet pack

[mikes-gh]

Description

AssemblyVersion and Version strings in assemblyinfo must be of the form a.b.c.d We remove -preview from the version string before packing to avoid a build fail.

How Has This Been Tested?

Using my repo to test. Publish fails due to security but you can see the successful build and pack. https://github.com/mikes-gh/MudBlazor/actions/runs/9078804072/job/24946625714#step:5:1

Type of Changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation (fix or improvement to the website or code docs)

Checklist

• [x] The PR is submitted to the correct branch (dev).
• [x] My code follows the code style of this project.
• [ ] I've added relevant tests.

[henon]

Thanks Mike!